Recently, a linear solenoid is used in, for example, an automatic transmission, a variable intake and exhaust valve, etc. The linear solenoid is a solenoid that linearly changes a position of a valve body (movable body) in accordance with the supplied current. In controlling this linear solenoid, a dither control, which vibrates the valve body, is performed to improve a sliding property thereof by reducing the friction between a housing and the valve body such as a spool (for example, see Japanese Laid-open Patent Publication No. 2004-301224)
The aforementioned dither control is performed by supplying the current including a superimposed dither component, which is an Alternating-Current (AC) component, to the linear solenoid, and the amplitude of this dither component is controlled to be a target value. Therefore, the current supplied to the linear solenoid is detected more than once in one dither cycle so that the amplitude of the dither component supplied to the linear solenoid can be detected.
When this current detection is performed through the Analog-to-Digital (AD) conversions, it is desirable that timings of the AD conversions are appropriately set so that the amplitude of the dither component can be detected. The same is applied to the case where the detection of the current or the voltage supplied to a control target is performed through the AD conversions in a control device that supplies, to the control target, the current or the voltage including a superimposed AC component that is not limited to the dither component.